Coke and process of producing the same



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T. H. HALL COKE AND PROCESS OF PRODUCING THE SAME Filed Nov. 1921 Patented Nov. 22, 1927.

THOMAS H. HALL, OF NYACK, NEW YORK, ASSIGNOR TO THE I l CORPORATION OF NEW JERSEY.

50 2 TENT l-OFFICE.

BARRETT COMPANY, A.

COKE AND PROCESS OF PRODUCING THE SAME.

Application filed November 2, '1921. Serial No. 512,320.

This invention relates to a process of roducing coke from pitch, such as coa tar pitch and the like, and the product thereby obtained. Heretofore attempts have been made to produce a satisfactory'coke from coal tar and coal-tar pitch by using different types of retorts ;for the coking operation, such as a horizontal through-gas retort, a continuous vertical retort, or a horizontal cast-iron retort, all of which are well known in this art, but theresults have been unsatisfactory.

The horizontal through-gas retort is unsatisfactory because of the difliculties encountered, because of the high cost of oper ation, and because the coke is too light and porous to be satisfactory for many metallurgical purposes. I The continuous vertical "retort is unsatisfactory for coking pitch becontains a considerable amount of volatile matter.

A great need has, therefore, been heretofore felt for coke that is mechanically strong and, at the same time, free from deleterious products, but this need could not, prior to my invention, be supplied because coke heretofore obtained from coal tar was mechanically weak, that obtained from coal contained too large a percentage of sulfur and ash, while that obtained from petroleum usuallycontained a considerable amount of.

volatile matter and too high a percentage of sulfur and did not possess the requisite mechanical strength.

It is well known that there are tars which comprise a large number of hydrocarbons,

- a large portion of which can be removed by distillation. The residue left after distilling these tars is commonly known as pitch. The

melting point of this residue orcpitch depends mainly upon the extent to which the distillation has been carried. Coal tar,for example, contains very little sulfur and ash,

. so that the pitch formed therefrom is likewise-substantially free from sulfur and ash; I have, therefore, found it preferable to use coal-tar pitch in carrying out my process, although other similar pitches may be'used.

By the present invention, pitch, such as coal-tar pitch and the like, may be usedto economically produce coke of a quality heretofore unknown by employing the well known beehive type of oven which is circular in horizontal cross section, or the Belgian type which is of a somewhat rectangular shape in horizontal cross section, with which to coke the pitch although the process does not depend upon the exact shape of the oven.

'- In this way a hard, tough coke, of sufficient strength to enable it to be used in and to support the charge in-foundry cupolas, can be produced. Since in the preferred embodiment of the invention a pitch is used which is substantially free from sulfur and ash, such as coal-tar pitch, the coke is likewise substantially free from sulfur and ash.

The so-called beehive oven, to which reference is made and which has been found to be suitable for practicing this invention, is of the type which has vertical walls'that extend upwardly for some distance and then converge or come together, an outlet or opening being left at the top for the escape of products of combustion. The type of oven which I have used with success is illustrated in the accompanying drawing, in which there is represented a sectional elevation of a beehive oven. In this drawing reference character 1 indicates the floor of the oven which may be circular in cross section; the oven has a sub-' stantially vertical Wall 2 and a dome 3. The

dome is provided at or near the top thereof with an outlet 4 for the productshof combustion and a side wall 2 is provided with a door 5 through which the pitch may be charged into the oven,- although the pitch is ordinarily charged thru the opening 4. in the top of the oven. Air ma be admittedthru the door 5 during the co 'ng operation and the coke may be withdrawn thru it after the cokingoperation has been completed. Bee-H hive ovens, such as that illustrated in this drawing, are old andwell-known and it is thought unnecessaryto describe the same more in detail. i Y

- In carrying out this invention a beehive oven, preferably having a temperature of approximately 1100 F. from apre'vious run,

is charged with pitchin substantially the face of the pitch. But if the pitch is charged lid into an oven, not from a previous run, combustion of the volatile constituents will read ily take place.

Combustion having been initiated, it has been found advisable to regulate the draft of air that enters the oven door so that the temperature does not rise above about 1400 F. until the coking of thepitch is well under way, after which the temperature may be omitted to rise to about 2200 F. Heat or the coking'operation is supplied by the combustion of volatile matter that is given ofi from the materials placed on the floor of the oven. The heat is applied to the material to be coked both by convection from the products of combustion and by radiation from the inner surface of the walls and roof of' the oven. During the coking operation the volatile constituents pass out through the top of the oven forming a flame, which flame .ceases when a s'ufiicient amount of volatile matter has been driven ofi', thus indicating that the supply of 'air should be diminished to prevent combustion of too large a portion of the pitch or-coke itself. It has been found that the coking begins along the top layer or surface of the pitch and gradually becomes deeper until the mass becomes poked. It has also been found that with coal-tar pitch of a melting point of about 250 F.450 F. containing about 25%50% of volatile matter, the coking o erationrequires from about 48 hours to- 1 a out 96 hours with charges of 5 tons to in which the temperature was 1100 F. The

pitch contained about 37% of volatile conibustible material and a fixed carbon content f about 63%. The draft was regulated so that a flame about 2 feet high came from the top of the oven, and as; the flame died down the draft was decreased to prevent combus tion of the coke. The coking time wasfabout' 64 hours, after which the coke was quenched by a stream ofwater while still in the oven,

and then the door was opened and the coke withdrawn. An analysis of the coke showed that it contained approximately 1% of volatile combustible material, about 98% of fixed carbon, 0.48% of'a'sh and 0.38% of sul fur, it was of a hard, firm structure with a silver-gray luster, and a test showed that it possessed a strength far above the minimum required for coke to be used in cupolas.

It is possible'to coke in this way pitch having a melting point of 250 F. 01' lower, and a volatile content of 50% or more by weight. The coke is substantially free from sulfur and ash, it has a: clear metallic ring,

is mechanically strong enough to sustain a cupola charge, and will maintain considerable mechanical strength even when heated to a glowing temperature, and it forms very little breeze or fine particles upon being handled. Its specific gravity is greater than is usually found to bethe case with pitch coke.

Its apparent specific gravity, as determined by method BGas Chemists Hand book, 1922, page 57, is between about (L9 and about 1.3, depending upon the porosity of the sample. Its true density, as determined by displacement in toluol at 25 (3., averages a little less than 2, being about 1.95 for most samples. The determination of true density, of course, presupposes the elimination of all air or other gases held in the coke, by the destruction of thepores or cells of the coke and thereafter suspending the coke so treated in toluol. placement which occurs, the true density is determined.

By coking pitch in the manned described, the heat is applied above the top of the material so that there is a gradual evolution of volatile combustible matter. In this way the simultaneous heating of a compara- From the distively large portion of the material to a stage where gases would be rapidly evolved is avoided, and a large part of the. volatile matter is dist-illedoif of each layer before a carburizing steel, and as asubstitute for other forms of carbon as a-reducing agent.

It has a low sulfur and ash cbntent and a hard, tough structure which enables it to carr a load in a foundry cupola; because of the low sulfur content of the coke,a larger pro ortion of low grade iron can be used In t e mix in a cupola in making'the same grade of finished material, than can be used when employing coke made from coal, thus materially lessening iron and steel production costs.

Iclaim: I 1. Mechanically strong metallurgical coke containing not more than about 0.38% of sulfur and 0.48% of ash. 5 2. Metallurgical coke containing not more I than about 0.38%.of sulfur and 0.48% of comprises charging an pompri'ses charging normal size charge of foundry cupola.

containash and The process of producing coke which an. oven of the beehive type with coal-tar pitch, having a melting point between about 280 and about 450 F., initiating within the oven combustion of volatile constituents of said pitch and concomprises a charging an sufiiciently to coke the tinuing said combustion sufficiently to coke the pitch. I

7. The process of producing coke which comprises charging an oven of the beehive e with coal-tar pitch, having about volatile matter, initiating within the oven combustion of volatile constituents of aid pitch and continuing said combustion suciently to coke the pitch.

8. The process of producing coke which comprises charging an oven of the beehive type with coal-tar pitch, initiating within the oven combustion of volatile constituents of said pitch, maintaining the temperature of the oven at a coking temperature below 1400 F. untilcoking has started and-then permitting the temperature to rise to and remain at about 2200" F. until the pitch is coked. v 9. The process of producing coke which oven of the beehive type with coal-tar pitch, initiating within the oven combustion of volatile constituents of said pitch, continuing said combustion itclt and quenching the coke with water be ore withdrawing the same from said oven. 1

10. The process ofcokin coal-taritch which comprises applyin ieat to a od ofthe same from the top thereof downwar 4 ly and maintaining the temperature of saidbody between 1100 F. and 2200.F.

11. The process of coking coal-tar pitch which com rises applying heat to a body of the same rom the top thereof downwardly and maintaining the temperature of said and having a metallic ring when struck.

sufiicient mechanical v bodybetween 1100 F. and 2200" F. for

about 48 to- 96'hours.

12 The process ofcoking coal-tar pitch I which comprises introducing the same'into an oven of the beehive type at about 1100 F., regulating the air draft so that a flame about two feethigh comesout and decreas ing3the draft after the flame dies down. carbon, which is liquid which comprises supplying the heat for. coking first tov the upper portion of the mass and then progressively downward through the mass. f

14. The process of coking liquid coal-tar pitch which consists in cokin first the upper portion of the mass and t en coking. the

alance of. the mass progressively in a downward direction.

' 15. The process of coking liquid coal-tar The process of coking a mass of hydroit or liquefiable by heat,

pitchwhich consists in supplying the necessary heat for'coking first to the upper ortion of the mass, without heating the ial ance of the mass to the, large gas evolution stage, thus causing thecoking to progress gradually in a downward direction through the mass. p 16. The-process of producing coke which comprises applying heat to the -upper portion of a mass of coal-tar pitchuntil coking takes place and then applying heat to a lower portion of the pitch.

17. The process of coking liquid coal-tar pitch which comprises applyingfheat to an upper portion of the mass until coking takes place and maintaining lower ortions of the. mass in a liquid but non-coking condition until the said upper portion is coked.

18. The process of producingcomprises charging an oven -o the beehive coke which a Job type, having a temperature of between 1000 F. and 1400 F., with coal-tar pitch, there by initiating combustion of volatile con.-

stituents of the pitch, and continuing combustion of volatile constituents of the pitch in heat exchange relation therewith sufii ciently to coke the pitch.

19. The process of producin comprises charging an oven 0% the beehive type, having a' temperature between 1000 F. and 1400, F., with coal-tar pitch, maintaining the temperature below about 1400 F. by combustion within the oven until .coking. has started, then. permitting the temperature to rise to about 2200 F. and maintaining it at about that temperature until coking is complete. 20. The process of coking amass of coaltar pitch which comprises charging it into an oven of thebeehive type, applying heat in the form of radiant energy to the top surface of the mass and then supplying additional heat by allowing combustion of the volatile constituents f the mass as they escape from the top surface of the mass;

coke which 21; The process of coking .coal-tarpitch which comprises charging the pitch into an oven of the heehive'type and, by the application of heat to the upper surface of the pitch, causing combustion of volatile cons'tituents of the pitch to be initiated and ooking progressively from the to surface downward to take lace, and al owing comhus-' '22. Mechanically strong metallurgical coke containing approximately 98 fixed c arbo'n,

less than 0,53% sulphur and less than 0.5%

ash.

23."Hard, tough coke containing approximately 98% fixed carbon, less than 1% volatile matter and having a true density slightlivI less than 2.

24. 0.5% sulphur and having a true density slightly less than 2.

. 25. Mechanicall strong coke containing less than 0.5% su phur, less than 0.5% ash and having a true density of between 1.9 and 2.

THOMAS H. HALL.

In testimony whereof I aflix my signature. I

ar'd; tough coke containing less than V 

